See attached: Unravelling drivers for the spatial distribution of diatom communities in eutrophic wetlands

Freshwater habitats harbor diverse communities of benthic phototrophic micro-organisms such green algae, diatoms and cyanobacteria. Especially diatoms occupy a wide range of different substrates such as sediments, rocks or water plants and represent very different life strategies featuring either permanent attachment, migratory movement, or colony formation. Diatom species have been intensively used to indicate the quality of inland waters, and especially under the current European legislation, assessments of ecological quality are essential. This study aimed to better understand the relationship between diatom species distribution and environmental parameters and to strengthen ecological monitoring in the Dutch lowlands. I used a tiered model of species selection presuming environmental filtering at local and regional scales and introduced aspects of spatial ecology from studies on macroscopic organisms. Diatom communities in eutrophic ditch systems in the lower part of North Holland were investigated: many of these ditches were located in peat lands. I pursued the following objectives: 1. to determine the dominant drivers dictating the distribution of diatom species with special emphasis on the role of water turbidity, 2. to weigh the importance of sampling design, and 3. to test and optimize ecological monitoring based on diatoms.